The characteristics of large bowel cancer in the low-risk black populationof the Witwatersrand

Sporadic colorectal cancer may follow a different pathogenic pathway in low -risk populations, The black population of the Witwatersrand has been urban ised for a long time, and has a westernised lifestyle, but colorectal cance r is still infrequent. This study aimed to define the characteristics of th e disease in this group. All histologically proven large bowel cancers aris ing in blacks resident in the Witwatersrand in 1991 and 1996 were extracted from the registry records. Mean age was 54.3 years (range 16-90 years); 6% occurred before 30 years and 22% before 40 years. Male:female ratio was 1. 32:1. Over three-quarters of the tumours arose in the rectum and sigmoid; t here was no evidence of a right-sided preponderance. More than half the cas es were advanced at presentation, and nearly one third were mucinous or sig net ring on pathological assessment. Associated adenomata were rare (5.2%), suggesting a different pathogenic pathway from the classical adenoma-carci noma sequence.